Sewed connection



July 18, 1944. E. J. 'KING 2,353,960

SEWE'D CONNECTION Filed March 24, 1942 60' INVNTR. W U W ATTORNEY Patented July 18, 1944 UNITED STATES PATENT orrlcs SEWED CONNECTION Ernest King, New York, N. Y. Application March 24, 1942, Serial No. 435,975 2 Claims. 2-243) My invention relates to sewed connections in plastics and more particularly 'to a method of treating those sections of a plastic material which are connected, as by sewing, to another body.

There are many instances where an article of manufacture comprising sewed connections is used in a watery or oily environment and it is often extremely desirable to waterproof these connections. For example, in galoshes or hat sweat-bands, even if the material thereof is wa terproof, water or perspiration may seep in through needle-holes or the thread used may transmit the fluid by means of' a capillary or wick action. Accordingly, it is the object of this invention to provide means to waterproof such connections by sealing the needle-holes.

Another object of my invention is to eliminate this capillary action.

Other objects of my invention will be apparent I I ing to; this invention.

The term plastics" has a well defined meaning and generally refers to organic compounds which possess plasticity and can be broadly classified under two headings, the thermoplastic and the thermosetting products. The present invention is particularly concerned with the thermoplastic materials which include cellulose acetate, vinyl, styrol, methacrylic' acid derivat'ivesv and related materials.

It is well known in the art to produce thread for knitting'or sewing which is made from these materials andthis type of thread may be called thermoplastic thread.

Accordingly, sheet to is preferably of a thermoplastic resin as is' thread Ii. Inasmuch as it is desirable that the sheet It and thread II have similar characteristics, the thread and sheet may be of the same plastic material. As willbe here-- inafter described, however, this invention has definite advantages whether such plastic thread or ordinary cotton or silk thread is used.

In the article shown in Fig. 1, the thread I I has been sewn through the sheet l0 and, of course, a needle-hole is produced. Water or any other like fluid may seep through this needle-hole and also may be transmitted from one side of the sheet I 0 to the other by the capillary or wick action of the thread ll, since, as is known, capillary or wick action is induced by the character of the conductor.

This transmission of moisture may be prespongy vented by applying a solvent of the thermoplastic sheet ID to the needle-hole or by a simple rapid heat-sealing operation. The solvents adaptable for the particular thermoplastic resin employed are well known to those skilled in the art and in general, acetone, propylene oxide, ethylene dichloride, mesityl oxide, or the higher ketones are satisfactory. A simple heat-sealing operation can be performed with a soldering iron but the use of a solvent solution is preferred. It is also very desirable and efiicacious to fortify the solvent with the particular type of plastic used so that the evaporation of the solvent leaves an ad-' ditional deposit of the plastic at the needle-hole and through the thread, as will be hereinafter described, thus more positively coating the thread and sealing the hole. The solvent does not depend entirely on penetrating the needle-hole but by dissolving the adjacent portion of sheet ill, the

material" of the sheet is caused to flow so as to efiect the sealingof the hole.

A deposit of fortified solvent I2 is therefore applied as shown in the broken lines of Fig. 1. Assuming. the thread I I to be of the thermoplastic resin type, the sheet I0 is caused to flow around the needle-hole and the thread is likewise softened so that the thread ,II and sheet Ill fuse into an ing and all the needle-holes will be sealed in the manner described.

Since capillary action is induced by the spongy character of the thread, it is apparent from Fig. 2 herein that such action will be prevented because the thread has fused with the sheet into a solid mass. Tests have demonstrated perfect resist- I ance to the transmission of water both by needlehole seepage or capillary action.

Very good results are also secured by the use of ordinary cotton or silk thread. When the fortified solvent is applied, it is absorbed by the thread as it dissolves the sheet. The plastic saturated thread therefore fuses with the sheet and has the characteristics of regular thermoplastic sheet likewise fuse into an integral solidified mass wherein the needle-holes are sealed and the capillary action is prevented.

Various embodiments of my invention are possible, the primary concept being the use of a member of plastic material which is sewn and wherein the needle-holes are sealed and the thread is fused with the plastic material by dissolving the area wherein the thread penetrates the member so that the setting oi the dissolved area effects a fusion of the thread and material. Instead of using a fortified solvent, a strip of plastic material may be laid over the needle-holes and a solvent in the form of a. liquid or heat and pressure may be applied.

I have shown a preferred embodiment of my invention 'but it is obvious that numerous changes and omissions may he made without departing from its spirit. For example, while I have stressed the use of a thermoplastic base member, it is also possible to use a thermoplastic impregnated fabric or other material. Furthermore, the invention need not be restricted to waterproofing but may be applied where the sewed area is apt to permit the transmission of gas or any other fluid. The

degree which the solvent should be fortified is not at all critical or important since a highly fortified solvent will merely leave more of a deposit.

I claim:

1. A method of sewing so as to prevent fluid transmission through the sewed area which comprises sewing a waterproof-thermoplastic resin member with thermoplastic thread, applying a solvent of said thermoplastic member and thread over the resulting needle-hole so as to saturate the portion of said thread adjacent the needle- I hole and allowing the thermoplastic member'and thread to fuse and set.

2. A method of sewing so as to prevent fluid transmission through the sewed area which comprises sewing a waterproof thermoplastic resin member with thermoplastic thread, applying a thermoplastic fortified solvent of said thermoplastic member and thread over the. resulting needle-hole so as to cause the adjacent area of the thermoplastic member and thread to flow and allowing the thermoplastic member and thread to fuse and set.

ERNEST J. KING. 

